1. Field of the Invention
The present invention relates generally to solar cells, and more particularly but not exclusively to methods and structures for interconnecting solar cells in a solar cell array.
2. Description of the Background Art
Solar cells are well known devices for converting solar radiation to electrical energy. They may be fabricated on a semiconductor wafer using semiconductor processing technology. Generally speaking, a solar cell may be fabricated by forming P-type and N-type diffusion regions in a silicon substrate. Solar radiation impinging on the solar cell creates electrons and holes that migrate to the diffusion regions, thereby creating voltage differentials between the diffusion regions. In a back side contact solar cell, both the diffusion regions and the metal grids coupled to them are on the back side of the solar cell. The metal grids allow an external electrical circuit to be coupled to and be powered by the solar cell. Back side contact solar cells are also disclosed in U.S. Pat. Nos. 5,053,083 and 4,927,770, which are both incorporated herein by reference in their entirety.
Several solar cells may be electrically connected together to form a solar cell array. In a solar cell array, a conductive area coupled to a P-type diffusion region (hereinafter “positive pad”) of one solar cell is electrically connected to a conductive area coupled to an N-type diffusion region (hereinafter “negative pad”) of an adjacent solar cell. The positive pad of the adjacent solar cell is then electrically connected to a negative pad of a next, adjacent solar cell and so on. This chaining of solar cells may be repeated to connect several solar cells in series to increase the output voltage of the solar cell array. Back side contact solar cells have been connected together using a relatively long, single strip of perforated conductive material. U.S. Pat. No. 6,313,395, which is incorporated herein by reference in its entirety, also discloses the interconnection of several back side contact solar cells to form a solar cell array.